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FreeBSD-SA-13:09.ip_multicast                               Security Advisory
                                                          The FreeBSD Project

Topic:          integer overflow in IP_MSFILTER

Category:       core
Module:         kernel
Announced:      2013-08-22
Credits:        Clement Lecigne (Google Security Team)
Affects:        All supported versions of FreeBSD.
Corrected:      2013-08-22 00:51:37 UTC (stable/9, 9.2-PRERELEASE)
                2013-08-22 00:51:43 UTC (releng/9.1, 9.2-RC1-p1)
                2013-08-22 00:51:43 UTC (releng/9.2, 9.2-RC2-p1)
                2013-08-22 00:51:48 UTC (releng/9.1, 9.1-RELEASE-p6)
                2013-08-22 00:51:37 UTC (stable/8, 8.4-STABLE)
                2013-08-22 00:51:56 UTC (releng/8.4, 8.4-RELEASE-p3)
                2013-08-22 00:51:56 UTC (releng/8.3, 8.3-RELEASE-p10)
CVE Name:       CVE-2013-3077

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

0.   Revision History

v1.0  2013-08-22 Initial release.
v1.1  2013-09-07 Binary patch released for 9.2-RC1.

I.   Background

IP multicast is a method of sending Internet Protocol (IP) datagrams to a
group of interested receivers in a single transmission.

II.  Problem Description

An integer overflow in computing the size of a temporary buffer can
result in a buffer which is too small for the requested operation.

III. Impact

An unprivileged process can read or write pages of memory which belong to
the kernel.  These may lead to exposure of sensitive information or allow
privilege escalation.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.

2) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch http://security.FreeBSD.org/patches/SA-13:09/ip_multicast.patch
# fetch http://security.FreeBSD.org/patches/SA-13:09/ip_multicast.patch.asc
# gpg --verify ip_multicast.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

3) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/8/                                                         r254629
releng/8.3/                                                       r254632
releng/8.4/                                                       r254632
stable/9/                                                         r254629
releng/9.1/                                                       r254631
releng/9.2/                                                       r254630
- -------------------------------------------------------------------------

To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:

# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base

Or visit the following URL, replacing NNNNNN with the revision number:

<URL:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>

VII. References

<other info on vulnerability>

<URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-3077>

The latest revision of this advisory is available at
<URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-13:09.ip_multicast.asc>
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